1. Field of the Invention
The present invention relates to a semiconductor light-emitting device that can prevent difference in level from overlapping the light-emitting unit in an end surface.
2. Background Art
In a semiconductor light-emitting device that emits light from an end surface, an optical thin film is grown on the end surface by sputtering or vacuum deposition for controlling reflectance, preventing end surface deterioration, and elevating outputs. However, if the end surface that becomes the base has irregularity, the optical thin film also has irregularity to vary the refractive index. Therefore, to make the end surface be a flat mirror surface, a technique using the cleavage of a single-crystal wafer as shown below is generally used.
First, as shown in FIG. 21, electrode patterns 17 of semiconductor light-emitting devices are formed on a single-crystal wafer 12. Here, it is ideal to form the electrode pattern 17 of each semiconductor light-emitting device so as to be parallel to the cleavage orientation of the single-crystal wafer 12. FIG. 22 is an enlarged plan view of the electrode patterns shown in FIG. 21. The width of the electrode pattern 17 is narrowed in the cleavage region than in other regions, so that the cleavage of the single-crystal wafer 12 is not damaged, and the semiconductor light-emitting devices are used for image recognition in scribing or breaking described later.
Next, as shown in FIG. 23, scratches 24 are formed using a diamond needle 23 on desired cleavage lines 22 on one side of the single-crystal wafer 12 (scribing). Next, as shown in FIG. 24, a load is applied from the back side of the scratches 24 (breaking). Thereby, the single-crystal wafer 12 is cleaved originating on the scratches 24 along the cleavage orientation. Cleavage herein is performed from the right to the left in the drawings. By the cleavage, the end surfaces of the semiconductor light-emitting devices ideally have flat mirror surfaces.
In actual situations, however, since various thin films are grown on a single-crystal wafer 12, the normal development of cleavages is interfered. As a result, the cleavage 19 is deviated from a desired cleavage line 22 as shown in the plan view of FIG. 25, and difference in level 20 occurs on the end surface as shown in the sectional view of FIG. 26. If the difference in level 20 overlaps a light-emitting unit 11, light-emitting properties and reliability are affected, and a defective device is produced.
In order to solve such a problem, a semiconductor light-emitting device as shown in FIG. 27 has been proposed (refer to e.g., Japanese Patent Application Laid-Open No. 7-086687). GaAs layers 34 and 35 are formed as clad layers on the upper and bottom surfaces of an active layer 33 required for light emission. Under the lower GaAs layer 35, a poorly cleavable AlGaAs layer 36 is formed. An element isolation groove 37 is deeper than the AlGaAs layer 36. By such a structure, even if the normal development of cleavage is interfered and difference in level occurs, since difference in level on the end surface are concentrated in the element isolation groove 37, the difference in level 20 is prevented from overlapping the light-emitting unit 11.